Regarding Michael's question of what you are trying to accomplish: First, is to get a transmission for which parts and replacements are readily available and inexpensive. A 38 year old German box that was made in the thousands is harder and more expensive to service than a Ford box that was made internationally in the hundreds of thousands.
Second, is First. First gear that is. The Pagoda first gear is good for parades and pulling trailers up steep inclines. Since I do neither, I'd like the transmission to take advantage of the torquey little engine and just get a move on. First wouldn't wind out the RPMs so quickly and then the step to second wouldn't be so high. Second is high enough to make starting off too hard on the clutch.
Third, I want to keep the lower ratio rear end for the quicker acceleration.
Fourth, every other car I have driven for the past 33 years has had a 5-speed and I keep trying to shift to it in the SL.
Fifth, it's my car and would make me happy.
Ray
'68 280SL 4-spd Coupe